Polypropylene (PP), a complex plastic, is generally considered safe for humans, considered one of the safest.
PP does not present stress-cracking problems and offers excellent electrical and chemical resistance at higher temperatures.
The major end-users of polypropylene are the packaging industry, followed by electrical and equipment manufacturing. The demand for this material is increasing due to covid-19.
Recommends that masks be at least three layers instead of two and that the third layer is a filter-type fabric, such as non-woven polypropylene fabric, adding a third layer to cloth face masks is now recommended for preventing the spread of COVID-19. Non-woven polypropylene fabric is the material of choice for this third layer.
Every study that has examined layering has found that using additional layers in face masks improves filtration, but some fabrics provide more filtration than others. We support the public health recommendation, and specifically, recommend the use of industry-grade “spun-bond” polypropylene, which is destined for the clothing and furniture industries has a fabric-like feel. It is washable and will not divert the supply of medical-grade polypropylene from the manufacture of formal personal protective equipment.
Non-woven materials, by contrast, have a random arrangement of fibers. This randomness enables high particle filtration while remaining highly breathable.
There are many types of non-woven polypropylene. The most common are spun-bond, melt-blown, and spunlaced materials.
Lightweight medical-grade spun-bond polypropylene, found in the outer layers of three-layer certified medical masks, has been tailored for medical uses. But as a single-use material, it is not designed to be washed. Do not recommend using melt-blown polypropylene for reusable non-medical masks.
Some of the most significant properties of polypropylene:
Chemical Resistance: Diluted bases and acids don’t react readily with polypropylene, which makes it a good choice for containers of such liquids, such as cleaning agents, first-aid products, and more.
Elasticity and Toughness: Will act with elasticity over a certain range of deflection (like all materials), but it will also experience plastic deformation early on in the deformation process, so it is generally considered a “tough” material. Toughness is an engineering term that is defined as a material’s ability to deform (plastically, not elastically) without breaking.
Fatigue Resistance: Retains its shape after a lot of torsions, bending, and/or flexing. This property is especially valuable for making living hinges.
Insulation: polypropylene has a very high resistance to electricity and is very useful for electronic components.
Transmissivity: Although Polypropylene can be made transparent, it is normally produced to be naturally opaque in color. Polypropylene can be used for applications where some transfer of light is important or where it is of aesthetic value. If high transmissivity is desired then plastics like Acrylic or Polycarbonate are better choices.
Here some of the disadvantages of Polypropylene:
Has a high thermal expansion coefficient which limits its high-temperature applications.
Susceptible to UV degradation.
Poor resistance to chlorinated solvents and aromatics.
Known to be difficult to paint as it has poor bonding properties.
Susceptible to oxidation.